Aerial propeller



Dec. 9, 1941. R. w. KLOEPFER AERIAL PROPELLER Filed May 21, 1940INVENTOR. BY /c/-MRD Hf. /l/LOEPFER ATTORNEYS Patented Dec. 9, 1941UNITED STATES yPATENT OFFICE AERIAL PROPELLER Richard W. Kloepfer,Teaneck, NIJ. Application May 21, 1940, Serial No. 336,321

(Cl. 17o-165) 2 Claims.

This invention relates to aerial propellers and has particular referenceto an improved four bladed propeller which is so constructed andarranged as to provide greater eiiiciency and economy of operation.

As the aerial propeller produces a turbulence in the air in the wake ofeach blade, it has been found desirable to so position the blades on thehub that the forward travel of the propeller will be such as to placethe leading edges of the blades forwardly of the disturbance or wakeproduced by the blades. This has led to the development of thetwo-bladed propeller with the blades diametrically disposed on the hubas most'practical and eilicient, since the blades being so disposedapart, th'e disturbance in the Wake of each blade will pass to the rearof the succeeding blade due to the translatory or forward movement ofthe propeller. It has also been found that in three and four bladedpropellers in which the propellers project radially from the hub in acommon plane at angles of 120 and 90 apart respectively that the forwardmotion of the craft is not suiiicient to carry the blades of thepropeller out of the wake of the preceding blades respectively and in anundisturbed air medium. It is, therefore, an object of the presentinvention to provide a four bladed propeller having the desirablecharacteristics of the two bladed propeller and which overcomes theobjections to the usual types of three and four bladed propellers.

' The invention, therefore, provides a four bladed propeller consisting'of two pairs of blades mounted on a common shaft to turn together andwhich pairs of blades project outwardly in opposite directions, theblades of each pair being pitched in the same direction and staggeredwith reference to each other to dispose one of the blades of each pairrearwardly of the other blade and in advance thereof in the direction ofrotation of the blades.

The invention further comprehends a four bladed propeller of theindicated character in which the blades are mounted on the hubtangentially of the shaft with the leading edges of the blades disposedin parallel relation and with the blades rotating in axially spacedorbits, one of the blades of each pair rotating in one of the saidorbits and the other blade of each pair rotating in the other orbit.

With the foregoing and other objects in view, reference is now made tothe following specilication and the accompanying drawing in which thereis illustrated the preferred form thereof.

In the drawing:

Fig. 1 is a view in side elevation of a propeller constructed inaccordance with the invention.

Fig. 2 is a front View thereof.

Fig. 3 is a top plan view.

Fig. 4 is a perspective view of thepropeller hub with the bladespartially broken away and with one of the blades removed and shown injuxtaposition. I

Referring to the drawing by characters of reference, the propellerincludes a hub designated generally by the reference character I0, whichis adapted to be aiiixed to the propeller shaft II for rotationtherewith in a counterclockwise direction as shown by the arrow in Fig.2.

The hub IIJ is preferably provided with a plurality of bosses I2 havingbores I3 extending longitudinally therethrough and opening above andbelow the hub, four bosses being show, two of which are located on oneside of the hub and two on the opposite side thereof and axially spacedfore and aft with the forward bosses in lateral alignment and the rearbosses in lateral alignment and the bores parallel and substantiallytangential to the shaft.'

The propeller further includes a plurality of pairs of blades I4 and I5and I6 and I1, the blades I4 and I5 constituting one pair and projectingoutwardlyl from the hub in one direction, While the blades I6 and I'Iconstitute the other pair 'and project outwardly from the hub in theopposite direction. Each blade is provided at its inner end with a shankI8 adapted to be received in the bore I3 of a boss I2, the blades I4 andI5 of the one pair being staggered with reference to each other torotate in axially spaced orbits, the shank of the blade I4 being mountedin the forward bore on one side of the hub, Whilefthe shank of the bladeI5 is mounted in the rear bore on the opposite side to thus dispose theblade I5 rearwardly of the blade I4 and in advance of the blade I4 inthe direction of rotation of the propeller. Similarly the blades I6 andI1 are staggered with reference to each other and in opposite relationto the staggering of the blades I4 and I5 to rotate in axially spacedorbits, the shank of the blade I6 being mounted in the bore on one sideof the hub and the shank of the blade I1 being mounted in the bore onthe opposite side of the hub to thus dispose the blade II rearwardly ofthe blade I6 and in advance of the blade I6 in the direction of rotationof the propeller. The propellers are pitched in the direction ofrotation and the driving faces I9 and 2o of the blades I4 and Is aredisposed in parallel planes, while the driving x faces 2| and 22 of theblades I6 and I1 are dis- L posed in parallel planes and with theleading edges, as illustrated, disposed in parallel rela- 3 tion. 1 i

In order tov provide means for securing the 1 28 of the boss. A nut 29engages over the threadassembled relation with the hub and to rotate theblade at the desired pitch.

In operation, the propeller, rotating in a A counter-clockwise directionas indicated by the arrow in Fig. 2, will exert a forward thrust by theblades I4 and I5 acting as a double screw and the blades I6 and I1acting as another double l screw. blade I4 in the direction of rotationand axially rearward thereof, the slip stream produced by the blade I4will not affect the density of the air in The blade I5 being in advanceof the the region of the blade I5 and similarly, the

blade I1 being in advance of .the blade I6 and axially rearward thereof,the slip streaml promore, the forward travel of the propeller will besuch that the following blades, such as the blades I6 and I1 willoperate in the air medium forl wardly of the vwake of the blades I4 andI5 rel spectively, land the slip streams of the forward blades I4 and I6will push rearwardly the turbulence in the wake of the lblades I5 and I1respectively so that the blade I5 will operate in the l compact slipstream of the blade I6 and the blade I1, will operate in the compactslip stream of the i blade I4 whereby the rear blades I5 and I1 will iincrease the volume and backward velocity of the 1 slip streams producedby the forward blades I4 and I6.

l ed terminal of the shank to secure the blade in 1 peller blades havingtheir inner ends `connected to saidv hub on opposite sides of the axisthereof in diagonally spaced apart relation and projecting outwardlyfrom the hub in the same direction,"

and a second pair of propeller blades havingtheir inner ends connectedto said hub on opposite and projecting outwardly from the hub in thesame direction and` opposite to the direction of said first pairofblades, and the blades of both pairs being pitched in the same directionand arranged with reference to each other to dispose one blade y,of eachpair axially rearward of the other and in advance thereof in thedirection of rotation and with one blade of each pair rotating in oneorbit and the other blade of each pair rotating in an axially spacedorbit, and means for securing the blades individually in selectivelyadjusted positions as to pitch.

2. In an aerial propeller, a hub having four parallel blade receivingsockets arranged with two sockets on one side of the axis of the hubspaced respectively forward and rearward axially and two sockets on theopposite side of the axis of the hub respectively spaced forward'andrearward axially, a pair of propellers having their inner endsrespectively vaflixed in two of `said i duced by the blade I6 will notaiIect the density 1 of the air in the region of the blade I1. Further-As illustrated, the blades are preferably'streamlined in cross sectionalconfiguration, the leading edges thereof being convex and merging intoconvex front faces which converge with reference to While the propelleris illustrated of may be reversed for clockwise rotation.

What kI claim is:

1. In an aerial propeller, a hub, a pair of prof sockets dispose saidblades on opposite sides of the axis of the hub in diagonallyl spacedapart relation projecting outwardly fromthe hub in the same direction,and a second pair of propeller blades having their inner ends affixed inthe remaining sockets t0 dispose said blades on opposite sides of theaxis of the hub in spaced` apart re v pose one blade of each pairaxially rearward of the other bladeof said pair and with the axialrearward blade in advance of the other blade in the direction ofrotation and with one blade of each pair rotating in one orbit and theother blade of each pair rotating in an axially spaced orbit, and meansfor holding the blades in the socket and for securing the sameindividually in selectively adjusted positions as to pitch.

RICHARD W. KLDEPFER.

